The invention relates to a method and an apparatus for the simultaneous damping of noise on the intake and pressure sides of fluid pumps as described in the claims appended hereto.
If fluid supply is accomplished with the aid of a fluid pump which is embodied as a piston pump or one of a similar type, for example, a positive-displacement pump, then the medium to be supplied is taken in, compressed, and expelled, with this process being repeated in rapid sequence. When a roller cell pump is used as the positive-displacement pump for the purpose of fuel supply, as is often the case, the intake, compression and expulsion process is repeated as often as there are discrete chamber volumes of the supply medium; that is, in the case of a five-celled roller cell pump, five times. Each of these pumping processes is associated with a brief drop in the intake underpressure and with an increase of the supply pressure. The pressure variations in the supplied medium which thus result, which form both on the intake and the pressure side of the pump and whose frequency is determined by the rotary speed of the pump, spread out in the form of sound waves (primarily those carried through solids) and thus, under certain circumstances, result in a high noise level in the pump.
If the noise-generating pump is a fuel supply pump in a motor vehicle or other mobile unit, then the most important cause of noise is that the pressure variations on the intake and pressure sides thereof are transmitted to the vehicle body (on the pressure side) and to the fuel tank (on the intake side).
The need thus arises for noise damping systems which damp pressure variations arising on the intake and pressure sides as close as possible to the point of origin and neutralize energy being released without restricting the functioning of the pump, and in particular accomplishing this at minimal expense.